University of Colorado at Boulder:

Thousands of years ago, ancient humans undertook a treacherous journey, crossing hundreds of miles of ice over the Bering Strait to the unknown world of the Americas.

Now, a new study led by the University of Colorado Boulder suggests that these nomads carried something surprising with them—a chunk of DNA inherited from a now-extinct species of hominin, which may have helped humans adapt to the challenges of their new home.

The researchers published their results in the journal Science.

“In terms of evolution, this is an incredible leap,” said Fernando Villanea, one of two lead authors of the study and an assistant professor in the Department of Anthropology at CU Boulder. “It shows an amount of adaptation and resilience within a population that is simply amazing.”

The research takes a new look at a species known as Denisovans. These ancient relatives of humans lived from what is today Russia south to Oceania and west to the Tibetan Plateau.

The Denisovans likely went extinct tens of thousands of years ago. Their existence, however, remains poorly understood: Scientists identified the first known Denisovan just 15 years ago from the DNA in a fragment of bone found in a cave in Siberia. Like Neanderthals, Denisovans may have had prominent brows and no chins.

“We know more about their genomes and how their body chemistry behaves than we do about what they looked like,” Villanea said.

A growing body of research has shown that Denisovans interbred with both Neanderthals and humans, profoundly shaping the biology of people living today.

To explore those connections, Villanea and his colleagues, including co-lead author David Peede from Brown University, examined the genomes of humans from across the globe. In particular, the team set its sights on a gene called MUC19, which plays an important role in the immune system. [Continue reading…]